A commonly used type of contact terminal comprises a stamped and formed conductive metal box-like socket. Contact terminals of this type are widely used, often in multicontact electrical connectors as well as in connectors containing only one or two terminals.
Contact sockets of this type must be dimensioned such that when the pin is inserted into the socket, a contact force will be exerted by the socket on the pin to form a stable electrical connection between the socket and the pin. Frequently, a separate contact spring is mounted on the socket such that when the pin is inserted into the socket, the spring is deflected, forcing the surface of the pin against the surface of the contact. In order to obtain a stable electrical connection between the inserted pin and the socket, it is desirable that the contact spring exert a relatively high force on the pin. Thus the force required to insert the pin into the socket is also relatively high. In other words, the greater the spring force, the greater the insertion force required to mate the pin with the socket.
High insertion forces, as described, are not desirable in high pin count pin-an-socket type contacts. As a result, such contact terminals are often designed with an acceptable insertion force requirement coupled with an acceptable contact force. One such method of obtaining acceptable contact force and insertion force is described in U.S. Pat. No. 4,550,972. The apexes of each corresponding pair of beams are spaced such that they are encountered sequentially during movement of the pin into the socket. This type of design allows for acceptable contact force and insertion force, however, problems have occurred. As the pin is inserted into the socket, there is a likelihood that the pin will be inserted at some relation relative to the socket because in practice it is unrealistic to expect the axis of the pin to align perfectly with the axis of the socket. Consequently, the beams will not be contacted at the same time or with the same amount of force, causing some of the relatively weak, flexible beams to be greatly deformed, exceeding the elastic limit of the contact material, thus causing permanent deformation and loss of contact force.
The present invention is directed to the achievement of an improved contact socket which is capable of exerting a relatively high contact force on an inserted pin and which does not require an unduly high insertion force when it is mated with the contact pin. Additionally, the beams of the socket are designed to compensate for lateral displacement of the pin and to allow the pin to be inserted at an angle relative to the socket with no harm being done to the beams, i.e. no permanent set which allows the beams to retain their resilient characteristics.